The present invention relates to a method, apparatus and product involving melt blowing systems and more particularly to an improved, highly efficient, low energy melt blowing process, a novel melt blowing die apparatus having a unique capability of accomplishing such process with a minimum of structural parts and a minimum of energy and a novel, highly efficient filter media product which can be readily produced by the inventive process and apparatus.
Non woven fiber mats formed by melt blowing dies and melt blowing processes for producing the same have been long known in the prior art. In this regard, attention is directed to the expired U.S. Pat. No. 3,825,380, issued to J. W. Harding et al on Jul. 23, 1974, which teaches the formation of such a fibrous mat from molten polymers by means of a longitudinally extending die apparatus having a triangular cross-sectional die nose configuration with a pair of oppositely directed attenuating air streams being directed along the die nose flanks toward centrally emitted melt blown fibers with the air streams flowing in opposed angular direction so as to include an angle therebetween in the range of thirty (30) to ninety (90) degrees, it being noted that the attenuated elongated fiber streams are cooled ambiently before collection on a screen as a web. In U.S. Pat. No. 4,714,647, issued to P. W. Shipp, Jr. et al on Dec. 22, 1987, sequentially deposited layers of melt blown thermoplastic filter fibers of different sizes are collected as a laminate web and in U.S. Pat. No. 5,236,641, issued to M. A. Allen et al on Aug. 17, 1993 melt blown polymer fibers are fed as strips to a collector by individually fed side-by-side melt blowing units, each unit having its through-put controlled to maintain the property in each strip at a predetermined value. Finally attention is directed to U.S. Pat. Nos. 4,486,161, issued to D. L. Middleton on Dec. 4, 1984; No. 4,818,463, issued to P. G. Buehning on Apr. 4, 1989; and No. 4,986,743, issued to P. G. Buehning on Jan. 22, 1991, each of which three aforesaid patents teaches a die tip structural arrangement for melt blown fiber material feeding.
Although the prior art teaches or suggests various overall die structures, die tip fluid material feeding structure and melt blowing processes, none teaches the unique and novel die construction, melt blowing process and resulting layered, fibrous filter web as is described herein.
In accordance with the novel features of the present invention, a straightforward, economical, easy to manufacture, easy to assemble and to maintain apparatus is provided, as is a unique melt blowing process requiring a straightforward and economical series of steps which provides an increase in fibrous filter media output with a minimum of energy consumption. In addition the present invention allows for straightforward and economical modifications in the novel process, apparatus and product to produce varying sizes and varying characteristic filter fibers in accordance with varying market demands. Further, the present invention provides a unique layered fibrous filter mat which serves to increase bulk with accompanying increased dust holding capacity and overall filtering efficiency.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.